1. Field of the Invention
The present invention is directed to starting elements, particularly a starting element having a hydrodynamic coupling element comprising a torsional vibration damper and a tuned mass damper.
2. Detailed Description of Prior Art
Starting elements for transmitting a torque from a drive unit to a downstream drivetrain such as a transmission are known in a variety of embodiments. Hydrodynamic coupling elements, i.e., hydrodynamic circuits without torque conversion (hydroclutches) or with torque conversion (hydrodynamic torque converters), are often used for enabling automatic starting. To increase energy efficiency after starting, they are mechanically locked up in a so-called lockup mode by converter lockup clutches to prevent flow losses and to optimize consumption of fuel or driving energy.
Starting elements or starting converters of this kind are often combined with torsional vibration dampers, which can comprise one or more stages and have a drive-side input element that can be connected to a rotating drive unit to be fixed with respect to rotation relative to it. Located between this input element and a driven-side output component are one or more energy accumulators or spring elements, for example coil springs, which can serve to suppress vibrations in the drivetrain. Accordingly, the torque is transmitted from the input component of the torsional vibration damper, via the energy-accumulating or vibration-damping elements, to the output component, which is connected to the output of the starting element so as to be fixed with respect to rotation relative to it. In general, a drive-side component is a component or assembly which, with respect to the flow of power from the driving unit to the end of the drivetrain, is located closer to the driving unit than a component designated as being on the driven side. In order to improve the damping action in two-stage torsional vibration dampers, the drive-side input element is initially connected via a first spring element arrangement to an intermediate transmission arrangement which is in turn connected via a second spring element arrangement to the output component of the torsional vibration damper.
Further, tuned mass dampers, as they are called, are also installed for further enhancement of driving comfort and further suppression of vibrations in the drivetrain, particularly with locked-up converter or locked-up hydrodynamic coupling element. Generally speaking, tuned mass dampers, or mass dampers, are additional masses coupled with the drive system or torsional vibration damper by a spring system. For example, a tuned mass damper operates on the principle that a vibratory system comprising a main mass and an additional mass is so tuned with respect to its natural frequency that at a certain excitation frequency the additional mass, referred to hereinafter as damper weight, carries out a forced vibration, while the main mass remains at rest so that vibration frequencies of this kind can be efficiently suppressed.
To achieve suppression of vibrations over a larger range of rotational speeds, speed-adaptive tuned mass dampers, or mass dampers, are used whose natural frequency or resonant frequency changes as a function of rotational speed, for example, proportional to the rotational speed. Thus by tuned mass damper is meant herein a device or mechanism or arrangement of components by means of which no torque is transmitted and which is capable of removing energy from the drivetrain at a determined, possibly variable, vibration frequency in order to suppress torsional vibrations occurring at this frequency.
A substantial challenge consists in arranging a plurality of such components or assemblies in a starting element in an efficient and space-saving manner such that the range of forces acting dynamically on the individual components can be absorbed.